Pressure centered control valve



March 15, 1960 J. A. KRAPF 2,928,380

PRESSURE CENfrERED CONTROL VALVE Filed Dec. 4, 1957 K 56 5 Z9 /8/95 yf/525575055 58 4l 6665 50 46 425/ 45 ,5f f/f/ y /ffw/ 64 John Albert Kraff United States Patent 'O 2,928,380 rarissima CENTERED CONTROL vALvE .lohn Albert Krapf, Cleveland Heights, Qhio, assigner to Gerland() Tuttolomondo, Cleveland, Sino Application December 4, 1957, Serial No. 700,595

4 Claims. (Cl. 121-465) This invention relates to Vvalves for directing flow of fluid in a fluid pressure system and more p-articularly to valves of the type that are movable in either direction from an intermediate position to direct the flow of iluid under pressure from a pressure line through the val-ve, this application being a continuation-in-part of my copending application Serial No. 247,340, led September 19, 1951 upon which Patent No. 2,826,178 was granted March 1l, 1958.

The valve of the p-resentinvention is of the automatically centering type, being provided with centering cylinders that are connected `at all times to the pressure line and that have pistons that apply opposing thrusts to the valve and with actuating means for moving the valvein either direction from its neutral position in opposition to the line pressure acting upon one of said cylinders. T' e force required to shift the valve from its intermediate or neutral position is always proportional to the line pressure so that the valve may provide means in vaddition to the usual gauges for indicating undesirable changes in line pressure. Y One of the centering pistons is preferably provided with a pressure face area greater than the other and a stop is provided in the path of this piston that limits the valve actuating stroke thereof and that is positioned to stop the same at a point Where-theV valve member has reached its intermediate or neutral position so that the valve is normally held by the pistons in said intermediate or neutral position. l

The valve is preferably of the sliding piston type with an end portion projecting through an end of the valve casing for connection to external operating means and, to simplify the valve structure, one of the centering pistons ispreferably of the sleeve type and slidably mount ed upon an end portion of the valve member.

The invention has for important objects to provide a rugged and durable valve suitable for high pressure hydraulic systems, to provide a simple and Ycompact construction for a pressure centered valve Vof the sliding piston type which has a portion extending through an end of the valve casing for connection to external aetuating means, and to provide a manually operated pressure centered control valve that requires a force proportional to existing line pressure to move it in either direction from its intermediate or neutral position so as to indicate to the operator undesirable or dangerous variations in line pressure.

Reference should be had to the accompanying drawings forming a part of this specification in which:

Figure 1 is a diagrammatic viewV showing the valve of the present invention employed as -a pilot valve in ahydraulic system;

Fig. 2 is a longitudinal section through the control valve of the present invention showing the same in its neutral position; Y A f Fig. l3 isla fragmentary longitudinal section on an enlarged scale showing the pressure centering pistons in positions where the valve is shifted from its intermediate or neutral position against the pressure in one of the 4valve centering cylinders; and 'Y Fig. 4 is av longitudinalsection through a control valve of modied construction. t

The present invention is applicable in general to valves of the type which are movable in either direction from an intermediate or neutral position to direct ow of fluid. f "f In Fig. 1 of the drawings, a control valve embodying the present invention, Which'is indicated -by the reference character A, controls the operation of la main valve B which serves to connect a hydraulic pressure line C or a drain line D to service conduits F and G extending from the valve B to a hydraulic motor E which is herein shown as ajcylinder` and piston. lThe valve B,

duits c and d and is connected through service conduits Y f and g with actuating cylinders 'f' and g for shifting the main valve B. The control 'valveA serves to apply pressure to the cylinderY g through the conduit g` andV to simultaneously connect the cylinder f', through the conduit f, to the drain line D to actuate the valve B in one direction and to connect the conduit f to pressure and the conduit Yg to drain to actuate the valve B in the opposite direction'.

As shown in Figs. 2 and body portion 2 that has a longitudinal bore from one end to the other thereof that provides a valve chamber that is closed at the ends'by end closure members 4 and 5 and that receives a sliding piston type valve member 6. The valve member 6 has axially spaced enlarged piston portions 7 and 8 that have a sliding fit in the valve chamber 3. with a circumferential reces-s 9 that is centrally disposed with respect to two circumferential recessesl() and )11 that are axially spaced from the recess 9 at opposite sides thereof. A pressure inlet port 12 connects Vthe recess 9 with ,the pressure line C, outlet ports 13 and 14 connect the recesses 10 and 11 with the service conduits f and g anda drain port 1-5 connects both ends of the valve chamber to drain, the valve casing 1 being provided with a passage 15a which connects both'fends of the valve chamber 13 Withrthe port 15 Vso that pressure on the end closures tending, to cause leakage is prevented. In the intermediate or neutral position ofV the valve member 6, the enlarged Yportions 7 and 8 thereof normally engage the cylindrical Wall of the chamber 3 between the central recess 9 and the recesses 13 and 14 i so that both of the service lines f and g are disconnected from the pressure line D. Movement of the valve members 6 in'one rdirectionconnects the outlet port 13 to pressure and movement of the valve member in lthe opposite direction connects the outlet port 1'4 to pressure. The ports 13 and 14 are both connected to drain in the inter-mediate position of the valve member 6, the

valve member y6 being movable in one direction to move the piston portion 7 across the recess 10 to a position is providedV with a cylindrical bore 18 in which the f-e`x- 3, the valve A has a easing indicated generally by the numeral 1 that comprises a- Thervalve chamber 3 vis providedV tension 16,its. The closure-lis detachably secured by suitable means to the valvejbody 2 and is provided with a positioning projection 19 that fits in the bore of the Lqlaarnbter.` 3. The valve member-f6 is actuated .by Vmeans of a lever 20 that is pivoted ahoveits lowenend to a closure member 4, the lower endof the-lever beingicongreeted to the extensionv '16 to imp'art; slidingmovements tothe valve'6. In theintermediate orj neutral position @of the valve, 6 the lever 20 is, in verticalposition so that by moving the lever 20 in one direction from its `vertical position, pressure is supplied to the service con- .duit f, and d'by moving it inajthe opposite direction pressure is .supplied to the service 4conduit-g. Aisealing I'jring'22 mayv be provided in the closure member 4 to prevent jleakage of `iluid throughthe borej18.

.-The end closure .-hasrinner, intermediate andv outer parts 23, 24y and 25; The innerpart 23 hasa cylindrical projection 26'that fits in a bore of the chamber 3 and Aan `outer cylindrical projection 27 that fits in an axial bore23 in theintermedi'ate member 24. The intermedi- Yate member Z4 has a counterbore 29 opening to its outer 4its ver tlcal position. vMovement of the lever 20 to the i Yneutral position where the piston 36 engages the inner end of the projection '32. Movement of the actuating Y lever in 'either' direction is opposed by the line pressure end which is'of slightly 'greater diameter than the bore 1 28. At the inner end of the counterbore 29 an internal AVcircumferential recess 30is provided that-opens to a passage` 31 in the valve casing that connects the recess 30 Ywith the passage 15a and drain port 15.' The outer part of the closure member 5 has a cylindrical proljection '32 that lits in the counterbore 29 and that extends into the circumferential recess 30. The member- 25 has ;an,axial bore 33 opening at its inner end and terminating short of the` outer f ace of the member 25 and a Acounterbore 34 at the inner end of its projection 32. In

order to connect the counterbore 34 at all times to drain, slots 35 are provided in the portion ofjthe `projection 32 vthat is positioned within the circumferential recess 30. The bore 28 serves as a fluid pressure cylinder and receives a sleeve piston 3,6 thathas a sliding t on the` extension 17VV of the valve member 6.V Y The sleeve piston 36 is engageable with an enlargement 37 onthe outer fend of theVV extension 17 to Yimpart a vmovement to the -valve The enlargement 37 is o f a diameter less than that of the counterbore 34 so that it may be moved into the counterbore 34, and the sleeve piston 36 is engageable with the inner end of the extension 32 of the outer closure part 2S, which serves to limit,;the v movement of the Vpiston 36. A piston 38 slidably lits in the bore 5.33 and has an enlarged end 39 at itsinner end that engages with the outer end of the extension 17.

A passage 40 in the valve casing 1 connects the cir- .,cumferential recess 9, which is open at all times to the pressure line C, with the bore 28 inwardly of the sleeve piston 36 and with the outer end of the bore 33, so that the piston 36 is subjected atlall timesto line pressure pressing it against the enlargement 37- and the piston 538 is. subjected at all times to line pressure pressing Vit inwardly toward the piston36. The pressurelface area .t oft the sleeve piston 36 `is greater than the pressure face area of the piston 38 so that the piston 36 is normally ...held in engagement with the inner end of the projection ,-32.- Pressure vacting on the piston 38 holds the enlargement 37 in engagement with the outer end of the pistonl .-36 and,when the'pistoni 36 is. in engagement with the inner end of the projection 32,rthe valve member is held in its intermediate or neutral Vposition with the-lever 20 vertical, as shown in Fig; f2ofgthejdrawings j, When the lever 20 is.V moved to the left fromV the posij tion shown in Fig.z42, the valve,rnerrlberl- 6-is moved in the opposite direction, moving the enlargement 37 away 'strom the piston36 .and into thecounterboreg34, as shown FigfS Yof the drawings.;Milieul the lever 20 isv ref leasedv the line-,pressure `acting on, the piston38rrvforces the valve -6 'to the -left' until-'thef enlargement Y37` is in engagement witlrthe piston 36, returning the valve to Tits intermediate or neutral position and the` lever 2,0 to

acting` upon one of the pistons 36 or 38 which oiers a resistance to movement ofthe valve which is proportional to the pressure existing in the pressure line C.

In the event of an undesirable or dangerous increase or decrease in pressure inthe line VC, the feel of the lever 20 would direct the operators attention to the fact and enable him to quickly take steps to remedy the situation. By employing centering pistons of different pressure face area, `the centering of the valvecan be effected ,byrmeans of a singlestop @in` thepath of the piston of greater pressure face area. By employing a sleeve type piston forone of the centering pistons, a simple and compact construction is provided for pressure centering a valve of the sliding piston type which has a part extending through an end of the valve casing for connection to an external actuating means.

In Fig.\4 of the drawings, a controlvalve of slightly This valve has a casing 41 provided with a body portion42 having a longitudinal ,bore that provides a valve chamber 43 that is closed by end closures 44 and 45. u Within `the valve chamber Vthere is mounted a pistontype valve member 46 which has axially spaced enlarged piston portions 47 and 48 that have a sliding tit Yin the bore of the chamber 43. A circumferential recess `49 `is provided in the` valve chamber 43 which is centrally disposed with, respect to similar circumferential recesses 50 and 51 axially spaced therefrom. The recess 49 communicates with a pressure inlet port 52 and the recesses 50 and 51 communicate with ports 53 and 54 which deliver to service con Vduits. i A drainport 55 is provided adjacent one end offthe valve chamber 3 and a passage 55a extending longitudinally through the valve member maintains communication between the ends of the valve chamber which are connected at all times to drain. As so far described, the valve of Fig. 4 is essentially the same as the valve shown in Figs. 2 and 3.

The end closure plate 44 has inner and outer parts 56 and 57, the outer part 57 has a central bore 58 in which Van extension 59 of the valve member 46 has a sliding t.

The inner part 56 of the end closure 44 has a bore 60 of larger diameter than the bore 58 in the `outer part 57, the bore 60 serving as a fluid pressure cylinder and having mounted therein a `sleeve pistonh61 that has a sliding lit on the extension 59 of the valvemember. The

inner end of the piston 61 extends into the valve chamber 43vwhich is provided with a counterbore 62 to receive the inner end Vof the pistonl. The sleeve piston 61 is engageable Vwith aring 63 that is slidable on the extension 59 and1 that is engageable with the body of the valve member 46and with a shoulder 64 at the inner end of the counterbore 6.2. 4Fluid pressure acting upon the an outer` part 69andg-thejinnerpart68is provided with a central bore 70.that is axially alined withgthe chamber i outerrend of` the sleeve piston 61 normally holds the ring 63 in engagement with the shoulder 64. A sealing ring 65 carried by the extension 59 4 engages the sleeve. piston 61 interiorly and a sealing ring 66 carried by the inner i closure part 56 engages the piston 61 exteriorly to prevent leakage of fluid through the part 56, and a sealing ring i 67 is provided in the outer closure part 57 to prevent leakage through the bore 58. r j

Thel closure 45 ,is fpr9vided--with1 an `inner part `68 and 43,'the1outer endgof the bore-70 .being closed by the outer part69;ofthe;closure member.Y `A pistonr71 in the bore 70proiects intqfthe vaLVecbamber. 43 for .-ensssei ment with the valve member 46. A passage 72 in the valve casing connects the pressure inlet 52 at all times to the outer ends of the bores 60 and 70 which serve as pressure cylinders for the pistons 61 and 71, so that the pistons 61 and 71 apply opposing axial thrusts to the sliding valve member 46.

The opposite ends of the valve chamber 43 into which the pistons 61 and 71 project are connected at all times to the drain port 55. The pressure face area of the piston 61 is slightly greater than the pressure face area of the piston 71, so that the piston 61 is normally held in its innermost position where it holds the ring 63 against the shoulder 64. Pressure acting on the piston 71 presses the valve member 46 against the ring 63 to hold the valve member 46 in its intermediate or neutral position as shown in Fig. 4.

The extension 59 of the valve member is pivotally connected to the lower end of a lever 74 which is pivoted to a bracket 75 carried by the valve casing. When the valve is in Aits neutral position the lever 74 is in a vertical position. When the lever 74 is moved to the left from its vertical position, the valve member 46 is moved toward the piston 71 against the pressure acting on the piston 71 while the piston 61 and ring 63 are retained in the position shown in Fig. 4. Movement of the valve member in this direction connects the pressure inlet port 52 with the service port 54, while the port 53 remains in communication with the drain outlet 5S. Upon release of the lever 74, pressure acting on the piston 71 returns the valve 46 to its neutral position. Upon movement of the Y lever 74 to the right from the position shown in the drawing, the valve member 46 is moved to the left, moving the sleeve piston 61 and the ring 63 outwardly against the pressure acting on the piston 61. Upon release of the lever, the iluid pressure acting on the greater pressure face area of the piston 61 will return the valvermember 46 to its intermediate or neutral position against the pressure acting upon the smaller pressure face of the piston 71.

It is to be understood that in accordance with the provisions of the patent statutes, variations and modifications of the specific devices herein shown and described may be made without departing from the spirit of the invention.

What I claim is:

1. A control valve for selectively connecting either of two service conduits to a iluid pressure line comprising a valve casing having a body portion provided with a bore extending from end to end and end members closing the ends of said bore to provide a valve chamber, said chamber having an inlet port to said pressure line and an outlet port to eachv of said service conduits, a piston type valve member slidable in said chamber in either direction from an intermediate neutral position to connect either of said outlet ports to said inlet port, means connecting both ends of said valve chamber at all times to drain, two valve centering cylinders, each in one of said end closure members and each axially alined with said valve member, an extension of said valve member extending into one of said cylinders, a sleeve piston in the latter cylinder slidably iitting therein and on said extension, a piston in the other of said cylinders engageable with said valve member,r one of said pistons having a pressure face area greater than the other, lmeans connecting said cylinders at all times to said'pressure line to apply thrusts in opposite directions to said pistons, means forming a circumferential shoulder lon said valve member against which said sleeve piston is pressed, a stop in the path of the piston of greater pressure face area positioned to limit the valve actuating stroke thereof at a point where said valve member has reached its neutral position, and means for applying an axial thrust to said valve member to move it in either direction from the neutral position in which it is normally held by said centering piston.

2. A control valve as set forth in claim l in which the two Valve centering cylinders are in one of the end closure members of the valve casing.

3. A control Valve as set forth in claim 1 in which one of the valve centering cylinders is in each of the end closure members of the valve casing.

4. A control valve comprising a casing having a valve chamber, a valve member movable in said chamber in either direction from an intermediate position, means for applying an actuating force to said valve member to move it in either direction from its intermediate position, two

valve centering cylinders in said casing, means for conn tinuously supplying uid at the same pressure to both cylinders, a valve returning piston in each of said cylinders that has a pressure face subjected to the pressure of said i'luid and that exerts a thrust on said valve member, the piston of one cylinder exerting a thrust on said valve member in a direction opposite that exerted by the piston of the other cylinder, one of said pistons having a pressure face area greater than the other, and means for limiting the movement of the latter piston in the direction in which it is moved by iluid pressure at a point where said valve is in its intermediate position, so that said valve member is relieved of the thrust of said piston of larger pressure face area when moved from its intermediate position against the thrust of the piston of smaller pressure face area. Y

References Cited in the iile of this patent UNITED STATES PATENTS 1,787,328 Schottler Dec. 30, 1930 2,614,539 Ernst Oct. 2l, 1952 2,615,433 Deardorl et al. Oct. 28, 1952 2,826,178 Krapf Mar. 11, 1958 FOREIGN PATENTS 527,171 Great Britain Oct. 3, 1940 

